Machines for inserting items, such as sheets of paper, for example, into envelopes are known in the art. A typical mail inserter is shown in FIG. 1. As shown in FIG. 1, the mail inserter 1 has an inserting station 5 wherein a collation or insert material is inserted into a receiving envelope. The mail inserter 1 comprises an envelope supply module 10 to supply the envelopes and a collation supply module 70 to supply the insert material. A typical insert material supply module has a plurality of feeders for separately releasing sheets of insert material onto a moving belt where the sheets of insert material are cumulated into stacks. The stacks of insert material are sequentially moved into the inserting station for insertion.
From the envelope supply module 10, envelopes are retrieved one at a time by an envelope retrieval mechanism 20 and the retrieved envelope is moved toward the envelope inserting station 5. Before reaching the inserting station 5, the flap of the retrieved envelope is opened by a flap opening mechanism 30. In the inserting station 5, the throat of the envelope is opened by a throat opening mechanism 40, so as to allow the insertion module 60 to move a collation (e.g., a pack of insert material) into the receiving envelope. After the insertion is completed, the stuffed envelope is moved away from the inserting station 5. A flap closing section 50 is used to close the flap of the stuffed envelope. The closed envelope is then sealed and further processed.
When envelopes having a window are processed for collation insertion, the edges of the window may present catch points as the collation is inserted. The catch points may cause a jam during the insertion process.